Many small internal-combustion engines, particularly two-cycle engines, are designed to operate on a gasoline and oil mixture for lubrication purposes. Such engines are widely used in marine applications and specifically in outboard drive units for propelling boats.
It is conventional to premix the fuel and oil for such engines. A typical volume ratio of gasoline to lubricating oil is 50:1. Such premixing involves several difficulties, particularly in conjunction with the English measurements used today in the United States. Gasoline is sold and measured in gallons, while lubricating oil is sold and measured in quarts, pints, cups and ounces. There is substantial room for mathematical error in making the necessary calculations to properly mix the two materials in a ratio such as 50:1. Furthermore, the gasoline and lubricating oil is typically mixed within a portable fuel tank. For proper mixing, the gasoline should be added to the lubricating oil. Consistent mixing or agitation is difficult to attain. If allowed to settle, there is a problem of resulting stratification of the two substances within the tank. These same problems exist on a larger scale where gasoline and lubricating oil are premixed by a vendor in larger stationary tanks and then pumped to the portable tanks of the ultimate users.
The present apparatus provides an electro-mechanical device for injecting measured amounts of lubricating oil into the fuel supply line connected to an engine. It mixes the oil on a demand basis so that only oil needed for proper lubrication of the fuel being immediately supplied to the engine is handled at any given period of time. It assures consistent mixing of the fuel and oil by handling both in small charges in a repetitive fashion. A self-contained device is provided separate from the engine and the normal fuel tank used with the engine. It requires no modification of engine operation and assures proper consistent lubrication during engine operation.